Ring cooling fan including stiffening ribs fully connected on at most two sides

ABSTRACT

A process of producing a ring cooling fan, the ring cooling fan including at least two fan blades, a fan hub, and a fan ring. Each of the fan blades has a distal end disposed away from the fan hub and connected with one another via the fan ring and a proximal end disposed on the fan hub. At least one of the fan blades includes at least two stiffening ribs in an open-box structure. The process includes disposing the fan hub in a mold, molding the at least two fan blades and the fan ring such that the stiffening ribs are disposed on a top surface of the fan blade and are fully connected with each other on at most two sides, and removing the ring cooling fan from the mold.

FIELD OF THE INVENTION

[0001] The present invention relates to a ring cooling fan, and, morespecifically, to a ring cooling fan including stiffening ribs fullyconnected on at most two sides (e.g., stiffening ribs having an open-boxstructure with more than one full side open, such that excess materialis absent from a full top side and at least a portion of another side ofthe stiffening ribs structure).

BACKGROUND OF THE INVENTION

[0002] In an internal combustion engine (e.g., a diesel or a gasolineengine), a ring cooling fan including multiple fan blades or impellersthat draw and/or push air through a heat conducting radiator can be usedto regulate the temperature of an engine coolant that cools the engine.As the performance level of the engine increases and/or the size of theengine compartment that houses the fan decreases, cooling requirementsof the fan increase.

[0003] The revolution rate of the fan blades can be increased toincrease the cooling rate of the engine coolant. However, because a fanthat is revolved at a higher rate undergoes increased stresses andstrains, the fan can warp or suffer catastrophic failure or “bursting”during operation, significantly and adversely affecting engineperformance.

[0004] To avoid such adverse effects, stiffened portions in the form ofa closed-box structure can be used on the fan blades at a location wherethe fan blades are molded on a center fan hub. In conjunction with theouter ring, such portions prevent warpage and bursting of the blades ofthe ring fan over a larger range of operating conditions and at higherrates of revolution. FIGS. 5a and 5 b show an example of such a ringfan. As exemplified in FIGS. 5a and 5 b, the ring fan 10 includesstiffeners 20 that are configured as the closed-box structure, such thatthe stiffeners 20 are fully connected on at least three sides (e.g.,each of the two stiffeners 20 and the three connecting sides forms afull face of a cuboid structure), thereby forming a box that has onlyone side open. It has been found that such a closed-box structure 20permits operation of the ring fan 10 at higher rates of revolution thana ring fan without such a structure while substantially impeding warpageand bursting of the blades 30.

[0005] The ring fan 10 is produced by an injection molding process. Insuch a process, the number of fans that can be produced by a singlemolding machine is proportional to the process time for injection of themolten plastic and cooling of the injection molded part. Accordingly, itis desirable to reduce the cooling time for the fan produced by amolding machine. For these reasons, it is desirable to produce a ringfan that is sufficiently rigid to preclude warpage and bursting duringoperation, while at the same time decreasing the cooling time andthereby allowing the ring fan to be produced in a more economicalmanner.

SUMMARY OF THE INVENTION

[0006] The present invention provides a process of producing a ringcooling fan, the ring cooling fan including at least two fan blades, afan hub, and a fan ring. Each of the fan blades has a distal enddisposed away from the fan hub and connected with one another via thefan ring and a proximal end disposed on the fan hub. At least one of thefan blades includes at least two stiffening ribs in an open-boxstructure. The process includes disposing the fan hub in a mold, moldingthe at least two fan blades and the fan ring such that the stiffeningribs are disposed on a top surface of the fan blade and are fullyconnected with each other on at most two sides, and removing the ringcooling fan from the mold. In a preferred embodiment, the stiffeningribs and the at most two connecting sides each form full faces of acuboid structure, thereby forming the open-box structure that is open onmore than one full side (e.g., open on one full side and at least aportion of another side), and more preferably, is open on two fullsides. The stiffening ribs are preferably connected with or to eachother via the structure of the fan blades. The present invention alsoprovides a ring cooling fan produced by such a process.

[0007] The present invention further provides a ring cooling fan. A fanhub includes a top surface and a bottom surface disposed apart from thetop surface along an axis of rotation of the ring cooling fan forconnection with a drive shaft or clutch body. A first fan blade includesa first distal end and a first proximal end opposite the first distalend and connected with a fan hub. A second fan blade includes a seconddistal end and a second proximal end opposite the second distal end andconnected with the fan hub, the first and second distal ends of the fanblades being connected with each other via the fan ring. At least twostiffening ribs are disposed on the first fan blade in an open-boxstructure, the stiffening ribs being fully connected with each other onat most two sides. In a preferred embodiment, the stiffening ribs andthe at most two connecting sides each form full faces of a cuboidstructure, thereby forming the open-box structure that is open on morethan one full side (e.g., open on one full side and at least a portionof another side), and more preferably, is open on two full sides.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] A more complete appreciation of the present invention and many ofthe attendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

[0009]FIG. 1 shows a bottom isometric view of the ring cooling fan ofthe present invention.

[0010]FIG. 2 shows a detail isometric view of the bottom of the ringcooling fan.

[0011]FIG. 3 shows a top view of the ring cooling fan.

[0012]FIG. 4 shows a detail isometric view of the top of the ringcooling fan.

[0013]FIGS. 5a and 5 b show top and bottom views, respectively, of aring cooling fan having a closed-box structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Examples of preferred embodiments of the present invention willnow be described with reference to the drawings, wherein like referencenumbers throughout the several views identify like elements. FIGS. 1-4show an example of a ring cooling fan according to the presentinvention.

[0015] In a broad embodiment, the ring cooling fan 10 includesstiffening ribs 20 that are disposed on a surface of a fan blade 40 andfully connected with each other on at most two sides, such that twostiffening ribs 20 and the at most two connecting sides (e.g., otherstructure of the ring cooling fan 10) each form a full face of a cuboidstructure, thereby forming an open-box structure that is open on morethan one full side (e.g., open on one full side and at least anynon-zero portion of another side). In a preferred embodiment, two sidesof the open-box structure are fully open. However, it is to beunderstood that the open-box structure includes, for example, thestructure that is open on one full side and that is open on another sideat least between about 10 and 100 percent (i.e., is closed between about0 and 90 percent) of a corresponding length of at least one of thestiffening ribs. In a more preferred embodiment, the open-box structureis open on one full side and is open on another side at least betweenabout 50 and 100 percent (i.e., is closed between about 0 and 50percent), and, in a still more preferred embodiment, is open on theother side between about 75 and 100 percent (i.e., is closed betweenabout 0 and 25 percent). However, it is to be understood that theopen-box structure includes the structure that is open on one full sideand that is open on another side within any ranges and/or subrangesdiscussed above. Disposing the stiffening ribs 20 on the surface of thefan blade 40 is to be understood to include the use of at least onesurface of the fan blade 40 as the connecting side so as to precluderequiring additional structural features (e.g., an additional ribattachment ring) between the at least one surface of the fan blade 40and the stiffening ribs 20. By this arrangement, excess structureassociated with an additional attachment ring, for example, can beeliminated. This arrangement results in a reduced volume of plasticbetween successive fan blades 40 and/or between the stiffening rib 20and the fan blade 40. In a preferred embodiment, the stiffening ribs 20are disposed on the surface of the fan blade 40 that is parallel to anaxis of rotation of the ring cooling fan 10. Fully connected stiffeningribs 20 are to be understood to include a connection between at least aportion of a length of the stiffening rib 20 and a full length of theconnecting side, as well as a full length of the stiffening rib 20 andat least a portion of the length of the connecting side. Such anarrangement facilitates removal of the ring cooling fan 10 from a moldduring a molding process, decreases cooling time in the mold of the ringcooling fan 10 during the injection molding process, and/or preventssticking and pull-outs of the stiffening ribs 20.

[0016] As exemplified in the drawings, the preferred ring cooling fan 10includes the stiffening ribs 20, a fan hub 30, a plurality (i.e., atleast two (2), preferably six (6), and more preferably ten (10) or more)of the fan blades 40, and a fan ring 50 (each discussed below).

[0017] In a broad embodiment, the fan hub 30 couples the fan blades 40with a ring cooling fan drive shaft (not shown) or clutch body (notshown). By this arrangement, a rotation of the drive shaft or clutchbody results in a corresponding revolution of the fan blades 40/ringcooling fan 10. It is to be understood that although the fan hub 30 andits associated structure shown in the drawing figures exemplifiespreferred embodiments, the fan hub 30 can include any structure so longas the fan hub 30 couples with the fan blades 40 for rotation.

[0018] As exemplified in the drawings, the fan hub 30 has a top surface31 and a bottom surface 33 that is offset from the top surface 31 alongan axis of rotation of the fan hub 30/the ring cooling fan 10. Each ofthe top and bottom surfaces 31, 33, have a generally circular crosssection, and include portions that are disposed on successive parallelplanes (i.e., neither of the top and bottom surfaces 31, 33, arerequired to lie entirely on a single plane). By this arrangement, in apreferred embodiment, the fan hub 30 is generally cup-shaped.

[0019] As exemplified in the figures, a plurality of about-circularholes 35 is used to connect the fan hub 30 with the drive shaft orclutch body. The plurality of about-circular holes 35 is preferablyabout equally spaced on the fan hub 30. In a preferred embodiment, theplurality of about-circular holes 35 includes four (4) holes that aredisposed about 90 degrees apart. The fan hub 30 can also include aplurality of radial slots 37. The radial slots 37 permit dissipation ofheat from the clutch body. The plurality of radial slots 37 is aboutequally spaced on the fan hub 30. In a preferred embodiment, theplurality of radial slots 37 includes four (4) slots that are disposedabout 90 degrees apart.

[0020] Optionally, the fan hub 30 can include interface holes (notshown) disposed on an outer diameter thereof. The interface holes can beused for flow through of liquid plastic during the molding process. Bythis arrangement, the fan blades 40 can be secured to the fan hub 30. Ina preferred embodiment, the fan hub 30 includes thirty six (36) suchinterface holes, each having a diameter of between 11 and 12 mm.However, it is to be understood that the any number of interface holesof any size can be disposed at a variety of positions on along thediameter of the fan hub 30. It is to be further understood thatsatisfactory attachment of the fan blades 40 with the fan hub 30 can beachieved in the absence of interface holes on the fan hub 30.

[0021] The fan hub 30 can be of a variety of materials, includingplastics and metals. In a preferred embodiment, the fan hub 30 is ametal capable of being disposed in a mold, such that at least a portionof the ring cooling fan 10 can be molded directly thereon. Specifically,the material can be steel, such as 050 YHK hot roll steel, aluminum, orglass filled nylon. However, it is to be understood that the fan hub 30can be of any material able to substantially impede bursting under thedesired operating conditions of the ring cooling fan 10.

[0022] In a broad embodiment, the plurality (i.e., at least two) of thefan blades 40 is connected with the fan hub 30, such that the fan blades40 effectively cool the engine. As exemplified in the drawings, in apreferred embodiment, the plurality of fan blades 40 includes ten (10)fan blades 40. It is to be understood that although the fan blades 40and their associated structure shown in the drawing figures exemplifypreferred embodiments, the fan blades 40 can include any structure solong as the fan blades 40 effectively cool the engine.

[0023] As exemplified in the drawings, each of the fan blades 40includes a proximal end 41 and a distal end 43 that is disposed apartfrom the proximal end 41. Contours of the top blade surface 45 and thebottom blade surface 47 are selected based on the desired operatingconditions and cooling requirements of the ring cooling fan 10. Asexemplified in the figures, at least two, and preferably, all of thedistal ends 43 of the fan blades 40 are connected to each other via thefan ring 50.

[0024] In a broad embodiment, the fan ring 50 connects at least two ofthe fan blades 40, thereby permitting desired operation of the ringcooling fan 10. Although the drawings show preferred embodiments of thefan ring 50 having a rectangular cross section and connecting each ofthe distal ends of the fan blades 40, it is to be understood that thefan ring 50 can be of any cross-sectional shape, and can connect any ofa plurality (i.e., at least two) of the fan blades 40 at any locationalong the length of the fan blades 40.

[0025] In a broad embodiment, the stiffening ribs 20 are disposed on asurface of a fan blade 40 and fully connected to each other on at mosttwo sides, such that two stiffening ribs 20 and at most two connectingsides form full faces of the cuboid structure, thereby forming anopen-box structure that is open on more than one full side (e.g., openon one full side and at least a portion of another side, and preferablyopen on two full sides). As discussed above, disposing the stiffeningribs 20 on the surface of the fan blade 40 is to be understood toinclude the use of at least one surface of the fan blade 40 as theconnecting side so as to preclude requiring additional structuralfeatures (e.g., an additional rib attachment ring) between the at leastone surface of the fan blade 40 and the stiffening ribs 20. For example,as shown in the drawings, in a preferred embodiment, the stiffening ribs20 are connected with or to each other via a side surface of the fanblades 40, the side surface being parallel to the axis of rotation ofthe ring cooling fan 10. The open-box structure including stiffeningribs disposed on the surface of the fan blades provides a number ofadvantages over a closed-box structure having a single open side asdepicted in FIGS. 5a and 5 b. It is believed that the closed-boxstructure acts as an insulator by restricting heat flow away fromfeatures of the mold. The open-box structure reduces cooling time andtherefore process cycle time by increasing heat flow away from thefeatures of the mold. Thus, by this arrangement, removal of the ringcooling fan 10 from the mold is facilitated, cooling time in the mold ofthe ring cooling fan 10 during the injection molding process isdecreased, and/or sticking and pull-outs of the stiffening ribs 20 isprevented. Generally, it is believed that these advantages are inverselyproportional to a size of a wall formed on the open sides of theopen-box structure (i.e., that these advantages decrease when theopen-box structure is open on one full side and a relatively smallportion of another side), and therefore are maximized when both sides ofthe open-box structure are fully open.

[0026] As exemplified in the drawings, in a preferred embodiment, thestiffening ribs 20 are used on both top and bottom surfaces of the ringcooling fan 10. However, it is to be understood that the stiffening ribs20 can be used on either or both sides of the fan blades 40.

[0027] In a preferred embodiment exemplified in the drawings, the topstiffening ribs 21 extend from the top surface 31 of the hub ring 30 tothe top blade surface 45 along the axis of rotation of the ring coolingfan 10 and extend along a radius of the fan hub 30/the ring cooling fan10 to an edge of the proximal end of the fan blade 40. The heights ofthe top stiffening ribs 21 can vary from each other, such that each ofthe top stiffening ribs 21 has a different height, and are preferablyarranged in order of ascending or descending height. The number, size,shape, spacing, orientation, and material of the top stiffening ribs 21can be selected such that the desired characteristics of the ringcooling fan 10 are achieved. For example, one or more of the topstiffening ribs 21 can be disposed at an angle to the radius of the fanhub 30, and one or more of the top stiffening ribs 21 can be disposedabout parallel with at least one other top stiffening rib 21.Alternatively, all of the top stiffening ribs 21 can be disposed in anyorientation, and can be disposed in different orientations relative toone another. Further, any number of the top stiffening ribs 21 can beused. In a preferred embodiment, three (3) to six (6) such topstiffening ribs 21 are used, and more preferably four (4) such topstiffening ribs 21 are used.

[0028] Similarly, bottom stiffening ribs 23 preferably extend from thebottom surface 33 to the bottom blade surface 47 along the axis ofrotation of the ring cooling fan 10 and extend along the radius of thehub ring 30/the ring cooling fan 10 to the edge of the proximal end ofthe fan blade 40. The heights of the bottom stiffening ribs 23 can varyfrom each other, such that each of the bottom stiffening ribs 23 has adifferent height, and are preferably arranged in order of ascending ordescending height. The number, size, shape, spacing, orientation, andmaterial of the bottom stiffening ribs 23 can be selected such that thedesired characteristics of the ring cooling fan 10 are achieved. Forexample, one or more of the bottom stiffening ribs 23 can be disposed atan angle to the radius of the fan hub 30, and one or more of the bottomstiffening ribs 23 can be disposed about parallel with at least oneother bottom stiffening rib 23. Alternatively, all of the bottomstiffening ribs 23 can be disposed in any orientation, and can bedisposed in different orientations relative to one another. Further, anynumber of the bottom stiffening ribs 23 can be used. In a preferredembodiment, one or a plurality (i.e., at least two) of such stiffeningribs 23 are used. When a plurality of stiffening ribs 23 are used,preferably two (2) to six (6) such stiffening ribs 23 are used, and morepreferably two (2) such stiffening ribs 23 are used.

[0029] Various other structural and material characteristics of thestiffening ribs 20 can be selected, in conjunction with the material andcharacteristics of the fan hub 30, such that undesired warpage andbursting of the ring cooling fan 10 is substantially impeded.

[0030] As discussed above, the ring cooling fan 10 is preferablymanufactured by an injection molding process. In such a process, the fanhub 30 is disposed in the mold. A feed stock is mixed, heated to a meltpoint, and injected at a specified pressure into the closed mold tocompletely fill the mold. During the injection process, the fan blades40 and the fan ring 50 are molded on the fan hub 30. At least twostiffening ribs 20 are molded on at least one of the fan blades 40, suchthat the stiffening ribs 20 are connected with each other on at most twosides, and, in a more preferred embodiment, such that the stiffeningribs 20 are fully connected on at most two sides (e.g., the twostiffening ribs 20 and at most two connecting sides each form full facesof the cuboid structure, thereby forming an open-box structure that isopen on more than one full side). The filled mold enters the coolingphase of the injection molding process, wherein the melted plasticsolidifies (i.e., changes from a liquid state to a solid state). Themold is opened, and the ring cooling fan 10 is ejected therefrom by oneor more ejection pins. Thus, the present invention includes a ringcooling fan 10 produced by such a process, as well as a ring cooling fan10 including the open-box structure produced by a different process.

[0031] Numerous additional modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, thepresent invention may be practiced otherwise than as specificallydescribed herein.

What we claim is:
 1. A process of producing a ring cooling fan, the ringcooling fan comprising at least two fan blades, a fan hub, and a fanring, each of the fan blades having a distal end disposed away from thefan hub and connected with one another via the fan ring and a proximalend disposed on the fan hub, at least one of the fan blades including atleast two stiffening ribs, the process comprising: disposing the fan hubin a mold; molding the at least two fan blades and the fan ring, suchthat the stiffening ribs are disposed on a surface of the fan blade andare fully connected with each other on at most two sides; and removingthe ring cooling fan from the mold.
 2. The process according to claim 1,wherein the stiffening ribs are disposed along a radius of the fan hub.3. The process according to claim 1, wherein the stiffening ribs aredisposed at an angle to a radius of the fan hub.
 4. The processaccording to claim 3, wherein the stiffening ribs are substantiallyparallel with each other.
 5. The process according to claim 1, whereinthe stiffening ribs have an open-box structure which is open on two fullsides.
 6. The process according to claim 1, wherein four stiffening ribsare present.
 7. The process according to claim 1, further comprising:molding at least two additional stiffening ribs on the surface of atleast one fan blade opposite the surface on which the originalstiffening ribs are disposed.
 8. A ring cooling fan produced by theprocess of claim
 1. 9. A ring cooling fan produced by the process ofclaim
 5. 10. A ring cooling fan produced by the process of claim
 6. 11.A ring cooling fan, comprising: a fan ring; a fan hub comprising a topsurface and a bottom surface disposed apart from the top surface alongan axis of rotation of the ring cooling fan for connection with a driveshaft or clutch body; a first fan blade including a first distal end anda first proximal end opposite the first distal end and connected withthe fan hub; a second fan blade including a second distal end and asecond proximal end opposite the second distal end and connected withthe fan hub, the first and second distal ends of the fan blades beingconnected with each other via the fan ring; and at least two stiffeningribs disposed on the first fan blade, the stiffening ribs being fullyconnected with each other on at most two sides.
 12. The ring cooling fanaccording to claim 11, wherein at least one of the stiffening ribsextends along a radius of the fan hub.
 13. The ring cooling fanaccording to claim 11, wherein at least one of the stiffening ribsextends at an angle to a radius of the fan hub.
 14. The ring cooling fanaccording to claim 11, wherein the stiffening ribs are parallel witheach other.
 15. The ring cooling fan according to claim 11, wherein thefirst fan blade includes a fan blade top surface disposed at a bladeangle from and adjacent to the top surface of the fan hub, thestiffening ribs extending from the fan blade top surface to the topsurface of the fan hub.
 16. The ring cooling fan according to claim 15,wherein four stiffening ribs are present.
 17. The ring cooling fanaccording to claim 16, further comprising: at least one bottomstiffening rib disposed on a bottom surface of the first blade oppositethe top surface.
 18. The ring cooling fan according to claim 17, whereintwo stiffening ribs are present on the bottom surface.